GMC Jimmy emissions

I have a 2005 GMC Jimmy and a few month ago the "Check engine" light went on. As per manual recommendation I changed the fuel, I was using low grade Esso and changed for Medium and High for the next two tanks and the light went off. It went on briefly later on and I decide to change completely to Petro Canada and since then I haven't have any problem.

Now my questions, in your experience which have been the fuel additive that have better improve the car emissions or clean better your system.

Comments

The only one I would consider would be Techron but I've never purchased any additive other than some Heet stuff umpteen years ago. I do buy Chevron now and then and they add a bit of Techron to that. Down here in the States, the EPA requires there to be a certain level of detergent additives in all gas sold, so additives generally aren't needed. link

I've heard that regular gasoline has the same amount of detergent as mid-grade and premium grades of gas too, but the marketers (Top Tier, etc.) claim that they add more detergent to their gas than what the EPA requires. Petro-Canada is a Top Tier retailer.

Is it possible that your CEL went off initially because the gas cap didn't quite seal completely?

I will second the Techron vote, but you might want to get the computer scanned to see for sure what set the code. There are other things that can "come and go" that you need to know about.

I just had one where the CEL would come on only when it was very cold (<40) outside. Turned out the thermostat was partially sticking open and wouldn't let the engine warm up within the pre-programmed time parameter. This was on an 02.

The EGR valve is a common source of the SES (Service Engine Soon) warning light. At least the EGR valve is a source of a SES error on pre-1992 S-series vechicles (and probably others too). I have a 1991 S-10 Blazer SUV and the SES light came on a few times after driving at a steady 70 MPH for a few miles after driving thousands of miles in stop and go city driving. Of course the light would go off after stopping the engine and restarting it in ten seconds. I solved th recurring SES light problem by driving at a sustained speed of 80 - 90 MPH for about 20 miles. I suspect the pentel in the EGR valve was stuck due to excessive carbon deposits. The constant low vacuum at high RPM for a sustained period loosened the pentel so it would not send error signals to the ECM.

At the present time, I am runnming a tank full of 93 octane so-called "premium" grade gasoline with a 5 - 1/4 oz. bottle of Lucas #10020 Fuel Injector Cleaner and lubricant. It may be my imigination but the engine seems to run better. The engine pinging under load is gone but that may be due to using the 93 octane fuel. My S-10 has 146,000 miles on the odometer and I am sure it has a substantial amount of carbon build up in the combustion chambers and valves, which will raise the static and dynamic compression ratio to the point the engine needs higher octane gasoline. Another reason a high milage engine requires higher octane gasoline is because oil contamination of the fuel-air mixture in the combustion chambers will raise the fuel octane requirement..

In my opinion, using a good fuel system cleaner and lubricant on a regular basis may help soften and eliminate carbon depostis and lubricate the fuel pump in the tank which will delay a fuel pump failure.

I have a 2001 GMC Jimmy 4X4, it sat in my mother in laws yard from October 2008 to March 1, 2009. I had to repair a few things before I could drive it. My husband took my Jimmy to have the emissions tested but it would not register when they hooked it up. What should I do?

First off, do not assume the problem is with your car. We just had the same issue on a Saturn that the inspection station claimed could not be "read". Take the vehicle to Autozone, or to anyone you know with an OBDII code reader and see if they can read it.

If the vehicle is running good, no CEL/SES light on, chances are that everything is okay and the inspection station needs to check out their equipment. There is a small chance that something ate some wires or such, damaging the data link to the diagnostic connector, but I would try getting the system read by another source before going down that road.